18 Mar 2025
Figure 1. Left: pre-operative mediolateral radiographic projection of a tibial from a dog with extreme tibial plateau angle and cruciate disease. Centre: photograph of proximal tibia exposed during surgery, demonstrating the location of three osteotomies: cylindrical tibial plateau levelling osteotomy (TPLO) and two straight osteotomies, connecting caudally to result in a cranially based wedge ostectomy (orange needle is located at the level of the intercondylar eminences). Right: postoperative radiograph demonstrating rotation of cylindrical osteotomy and reduction of wedge ostectomy, and fixation with a TPLO plate and single Kirchner wire/figure of eight tension band wire combination.
Non-surgical management of cruciate disease in dogs is not good. A study from 1984 showed that non-surgical management of cruciate disease in dogs could be successful in 86% of dogs weighing 15kg or less and 19% of dogs weighing more than 15kg (Vasseur, 1984).
Of course, literature from 1984 does not an “update” constitute. Pegram and others (2024) used target trial emulation (an epidemiological trick to crunch observational data) to show that surgical management (tibial plateau levelling osteotomy [TPLO], lateral stabilising suture, and tibial tuberosity advancement [TTA]) of dogs with cruciate disease reduces short-term and long-term lameness compared with non-surgical management.
In short, if we can, we should probably operate on dogs with cruciate disease.
This article aims to give an update on the surgical options available; my apologies, some of this delves a little deep.
The history of operating on cruciate-deficient canine stifles is well known. We had tensor fascia lata grafts, partial thickness patellar tendon grafts and hamstring grafts. Mostly, they were placed in some modification of the over-the-top approach (with the top referred to being the lateral femoral condyle). They tend to break down because canine cruciate disease fills the stifle with tissue-hungry macrophages and proteases.
Then we had lateral (and medial) stabilising sutures of various types, with variation in the material, the location of origin and insertion, the manner of fixation of the material, and controversy regarding isometry (that is, can a suture that crosses the canine stifle ever be at the same tension through a full range of motion?).
Outcomes were acceptable, but we all know that isometry cannot be achieved, so a suture is either too loose a lot of the time, or too tight and at risk of stretching or snapping, and a technique that relies on peri-articular fibrosis to stabilise a joint is one I would rather not be involved with.
In the 1990s, tibial osteotomies were documented to alter cranial tibial thrust, this being a feature either of the angle of the tibial plateau relative to the long axis of the bone in the sagittal plane, or a feature of the angle between the tibial plateau and the patella tendon, depending on which biomechanical model you favour.
In terms of updates in the past 30 years, no one has come up with anything new. But the companies that make veterinary orthopaedic implants have come up with new ways of doing the same old things, drawing us in with locking technology, titanium alloy, fancy colours, anatomical implants and increasingly diverse sizes to accommodate every size of dog.
Plus, we have become better at using these surgical techniques for dogs with more severe stifle disease.
What better way to kick off this article than with this controversy? Is TTA better than TPLO? Or is TPLO better than TTA?
Increasingly, the data suggests a superior long-term functional outcome for TPLO versus TTA. However, the data favouring TPLO remains based on small numbers. Krotschek and others (2016) showed that 15 dogs with TPLO did a bit better than 14 dogs with TTA in terms of returning to normal limb function over a year following surgery.
The case numbers in the studies are only really creeping upwards. In 2020, Moore and others showed that TPLO was superior to TTA in 118 dogs (166 stifles), 94 of which (133 stifles) had TPLO. Though this study appeared to be biased toward TPLO, with 33 TTA stifles compared with 133 TPLO stifles, the timeframe was good, involving only cases with more than three years of follow-up.
Methods included radiographic assessment of osteoarthritis progression and two client-completed questionnaires (canine brief pain inventory and canine orthopaedic index). TPLO cases had less progression of radiographic osteoarthritis, less pain and less interference with mobility.
Another recent study (Jeong et al, 2021) compared TPLO with TTA in purpose-bred beagles. These 15 poor dogs had both cranial cruciate ligaments transected and then had TTA on one stifle and TPLO on the other.
A useful study, undoubtedly, but a line crossed for this author in terms of ethics. The data is there, so we should use it: among these 15 dogs, there were late meniscal injuries in 11 out of 15 TTA stifles and 1 out of 15 TPLO stifles over 32 weeks. Gross pathological examination following euthanasia in these dogs also revealed more articular cartilage wear in the TTA stifles.
I would suggest that we still need greater numbers to be confident that TPLO outcomes are superior to TTA. Nonetheless, the international trend is towards TPLO, and we have witnessed this shift over the past decade as surgeons gradually drift from favouring TTA to TPLO.
Out of interest, a recent article described the revision of seven TTA cases using TPLO (Serrani et al, 2022), and I am unaware of any anecdotal cases in which the reverse (TTA performed to salvage persistently unstable stifles following TPLO) was performed.
Some of the reasons that TTA hangs on is that it requires less by way of specialist equipment (everyone has a sagittal saw, but not everyone has a TPLO saw and the cylindrical blades required for TPLO), and it is claimed that the technique is easier to learn. I would argue this latter point is not necessarily accurate, and there is at least as much scope for malpositioning or malaligning the osteotomy as with TPLO, not to mention a (anecdotally) greater risk of implant failure where technique is not optimal.
Perhaps to determine for certain which technique is superior, we need to look to the force plate for truly objective and controlled measures of outcome (such as the Krotschek and others study from 2016), but we do still need studies with bigger numbers.
There was a time when we would religiously sedate every dog for follow-up radiography six to eight weeks following TPLO. Now, two studies have questioned the value of this approach.
Alexander and others (2021) looked through the records of 1,010 dogs that had uncomplicated TPLO at multiple centres in England, Ireland and the Netherlands. Radiographic findings at routine radiographic follow-up resulted in changed management in 3.76% of cases, where clinical findings and prolonged use of analgesia were more sensitive predictors of complications.
This was a popular topic in 2021, because the same year, Olivencia-Morell and others found that 49% of 100 TPLO cases had minor complications not noted from physical examination (mostly patellar tendonitis, but also a few fibular or distal patellar pole fractures), but only in 2% were these considered worthy of an altered postoperative plan (two extra weeks of exercise restriction).
For postoperative, follow-up following TPLO, we should discuss history with the client and perform a thorough clinical examination, but perhaps we can reserve radiographic follow-up for cases with any suspicion of a concern.
It has been reported that there is a cohort of dogs with cruciate disease that presents with severe instability. The anecdotal report of such cases has prompted a number of manufacturers to drill a little hole in their TPLO plates, which is handy if we wish to place a lateral stabilising suture in addition to our TPLO.
In 2017, Schaible and others documented just such a cohort of dogs: 19 dogs to be precise, with 23 affected stifles. A combination of TPLO and lateral stabilising suture was performed in all cases. There was a 17.4% major complication rate and subjectively the outcomes were okay. The definition of severe instability was also very subjective. There are no reports of similar dogs being managed with TPLO alone.
Two questions are raised and not answered: do dogs with significant preoperative instability do better (or worse) if their TPLO is combined with a lateral suture? Also, might all dogs, regardless of the extent of their instability, do better (or worse) if their TPLO is combined with a lateral suture?
At this stage, I am not rushing out to buy an anatomical TPLO plate with a little hole at the front.
That said, to answer my own question regarding how to manage these cases, the vast majority can be stabilised with a well-executed TPLO. An additional lateral suture might be considered.
Extreme tibial plateau angle (eTPA) is defined variably, but usually is reserved for a tibial plateau angle greater than around 35° to 40°.
Often, eTPA is associated with previous tibial tuberosity avulsion and conservative management. If there is a proximal tibial physeal fracture concurrent to the tibial tuberosity avulsion, as there commonly is, the proximal tibial epiphysis can heal in a caudal position, having rotated such that the TPA is high.
Dogs with eTPA and cruciate disease cause a problem. A lateral stabilising suture will be under significant strain. A TTA would require the tibial tuberosity to be located in outer space to achieve a right-angled patellar tendon angle. TPLO would require rotation of the proximal fragment until the cranial aspect of the rotated fragment is located distal to the point of the tibial tuberosity (the so-called safe-point; Talaat et al, 2006), perhaps increasing the risk of tibial tuberosity fracture.
A cranial closing wedge can be performed, but the larger the wedge, the greater the inaccuracy in reducing the plateau angle and the greater the risk of inducing valgus or varus deformity when the osteotomies are not parallel.
In 2006, Talaat and others suggested a combination of cranial closing wedge ostectomy and TPLO, and this is my preference. In the study, 18 stifles in 15 dogs were operated, with good long-term outcomes, though with implant-related complications in 27.8% (Figure 1).
The technique essentially involves making a cranially closing wedge immediately distal to the TPLO. All osteotomies are marked on the bone.
The TPLO is rotated first and the craniocaudal fixation pin acts as an anchor for a figure of eight tension band wire placed to reduce the wedge ostectomy, which is completed second. The pin and tension band wire stay in place and the repair is augmented with a TPLO plate (Figure 1).
An alternative surgical technique for eTPA in dogs with cruciate disease was described by Frederick and Cross in 2017, and by Terreros and Daye in 2020. The modified cranial closing wedge ostectomy (CCWO) essentially involved the two osteotomies crossing cranial to the tibial caudal cortex to achieve a partially closing and partially opening ostectomy.
Decent outcomes were achieved, and this technique only has one osteotomy to bridge, though the tension on the distalised tibial tuberosity might be quite dramatic, so a cranial pin/tension band wire augmentation in addition to a medial plate and screws, was recommended.
A modification of the centre of rotation of angulation (CORA)-based levelling osteotomy modification has also been described by Schlag and others (2020). Before this article strays into the realms of the excessively esoteric, the CORA-based levelling osteotomy uses a TPLO blade upside down to allow rotation of the entire proximal tibial metaphysis cranially, and in the Schlag and others modification they used the same saw blade to make a second osteotomy, meeting the first caudally to make a curved cranially closing wedge, before rotating the proximal section cranially. The planning for this technique is complicated.
Overall, CORA-based levelling shows promise, but uptake of the technique has been limited.
We know that a significant proportion of dogs present with hindlimb lameness associated with concomitant cruciate disease and patellar luxation (41% of small breed dogs presenting with patellar luxation had cruciate disease in one study; Campbell et al, 2010).
We assume a good proportion of these dogs had subclinical patellar luxation prior to the onset of cruciate disease.
Nonetheless, at the time of stifle surgery for cruciate disease, it seems appropriate to stabilise the patella concurrently. Groove deepening alone can be useful; however, realignment of the quadriceps mechanism remains an important feature of any attempt to restore normal patellar tracking.
Interesting osseous techniques include a modification of the TPLO, first described by Langenbach and Marcellin-Little in 2010, and more recently documented by Flesher and others in 2019. In this technique, the TPLO is performed as usual, but the fixation involves medial translation of the proximal segment, sometimes with internal rotation, to effectively laterally translate and externally rotate the tibial tuberosity (which, you will remember, stays with the diaphyseal section of tibia) to realign the quadriceps mechanism.
A combination surgery involving TPLO and tibial tuberosity transposition for concomitant cruciate disease and patellar luxation has been documented, also in two studies: Leonard and others (2016) and Redolfi and Grand (2024). Both were retrospective studies, with 13 stifles in the former and 24 stifles in the latter publication.
Major complications (surgical site infection and recurrence of grade II medial patellar luxation) were apparent in the 2024 study, with none reported in the 2016 study.
Modifications of TTA have also been reported for concomitant cruciate disease and patellar luxation. Tibial tuberosity transposition advancement was reported in 2011 by Yeadon and others.
The technique advances and lateralises the tibial tuberosity using a modification of the usual implants, and was performed in this study in 39 cases.
There was medial patellar luxation recurrence in four cases and the actual tibial tuberosity advancement was less than expected, with advice from the authors regarding planning to achieve the appropriate advancement given.
No matter the surgeon’s preference for managing cruciate disease, we have good solutions for dogs with concurrent cruciate disease and patellar luxation. It is appropriate to address both in a single session.
This article has reported on some of the recent literature regarding cruciate disease.
New, excellent data is reported for this condition each year regarding modifications of old techniques, clinical outcomes data and advances in the biomechanics of the various techniques we employ. It is hoped the reader will have found this update useful.
